#include <iostream>
#include <vector>
#include <sstream>
 
using namespace std;
 
int main()
{
    int t, n;
    long long temp;
    vector<long long> factors;
    cin >> t;
    while(t--) {
        cin >> n;
        std::string line;
        getline(std::cin, line);
        std::istringstream iss(line);
        while (iss >> temp) {
            factors.push_back(temp);
        }
        for(long long x = 0; x < 32769; x++) {
            long long sum = 0;
            long long copyX = 1;
            for(long long factor : factors) {
                sum += copyX*factor % 32768;
                copyX = copyX * x % 32768;
            }
            if (sum == 0) {
                cout << x << endl;
                break;
            }
        }
    }
    return 0;
}
 

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

MgoxCjIgMQoyCi00MCAzIDE=

2
1
2 1
2
-40 3 1